The present invention relates to a gearshift lever that is operated to switch a gear range of a transmission installed in a vehicle or the like.
As known in the art, when a transmission in installed in a vehicle, a gearshift lever is used to switch the gear range of the transmission. The gearshift lever typically includes a detent mechanism to restrict unnecessary movement of the gearshift lever to a reverse range, in which the driving wheels of the vehicle are driven in reverse direction, or to a parking range, in which the driving wheels are locked. Japanese Patent Publication No. 3600631 describes a conventional gearshift lever including such a detent mechanism. FIGS. 1A and 1B schematically show the gearshift lever described in the publication.
As shown in FIGS. 1A and 1B, the detent mechanism basically includes a detent rod 51, which is inserted into a lever body 50, and a base plate 52, which has a detent receptacle 52a. The detent rod 51 has a basal portion on which a detent pin 51a is formed. The detent pin 51a is inserted into the detent receptacle 52a. The detent receptacle 52a has an upper inner wall surface in which a guide groove 52b is formed. The guide groove 52b includes a plurality of steps of different heights corresponding to different gear ranges. A coil spring 53 biases the basal portion of the detent rod 51 to hold the detent pin 51a in a state engaged with the guide groove 52b. The engagement of the detent pin 51a with the guide groove 52b results in the steps of the guide groove 52b restricting pivoting of the lever body 50 about a pivot shaft 54 of the lever body 50. The lever body 50 includes a distal portion on which an operation unit 55 is arranged. A user pushes and operates the operation unit 55. A coil spring 56 biases the operation unit 55 in a direction opposite to the direction in which the operation unit 55 is pushed (direction indicated by arrow d in FIG. 1A).
In this gearshift lever, when the user pushes the operation unit 55, a basal portion of the operation unit 55 pushes the detent pin 51a. This lowers the detent pin 51a against the biasing force of the coil spring 53. As a result, the detent pin 51a is disengaged from the guide groove 52b to release the lever body 50.
When the detent pin 51a is shifted, for example, from a position at which it engages the step of the guide groove 52b as shown in FIG. 1B is shifted to a position at which it engages a step D1, the detent rod 51 is moved downward from the position shown in FIG. 1B. The movement of the detent rod 51 forms a gap between the distal portion of the detent rod 51 and the operation unit 55. When such a gap is formed, the user may push the operation unit 55. In such a case, the user first counters just the biasing force of the coil spring 56. Thus, the user will first find the operation unit 55 as being relatively light until the operation unit 55 comes into contact with the detent rod 51. Then, when the operation unit 55 comes into contact with the detent rod 51, the user will counter the biasing force of the coil spring 53 in addition to the biasing force of the coil spring 56. Thus, the user will first find the operation unit 55 as being relatively heavy. Since the responsiveness of the operation unit 55 changes, the user may feel uncomfortable.
In the prior art, Japanese Laid-Open Patent Publication No. 2006-51862 discusses a method for biasing the operation unit in the same direction as the direction in which it is pushed. FIG. 2 shows the cross-sectional structure of a gearshift lever described in the publication.
As shown in FIG. 2, the gearshift lever mainly includes a holder 61, which is fitted into a lever body 60, an operation unit 62, which is pivotally supported by a first shaft 65 in the holder 61, and a link member 64, which is pivotally supported by a second shaft 66 in the holder 61. A torsion coil spring 67 is arranged on the first shaft 65 to bias the operation unit 62 in the direction in which the operation unit 62 is pushed (the direction indicated by arrow e in the drawing). The operation unit 62 includes an arc-shaped elongated hole 62a. A third shaft 68 of the link member 64 is inserted into the elongated hole 62a. 
In this gearshift lever, when the operation unit 62 is pushed in the direction indicated by arrow e, the operation unit 62 pivots about the first shaft 65 and pushes the third shaft 68 in the direction indicated by arrow e. This moves the third shaft 68 in the elongated hole 62a, while pivoting the link member 64 in a direction indicated by arrow f and pushing a distal portion of a detent rod 63. As a result, the detent rod 63 is pushed downward. In the gearshift lever, the torsion coil spring 67 biases the operation unit 62 in the direction indicated by arrow e. This constantly biases the link member 64 in the direction indicated by arrow f. Thus, even when the detent rod 63 is moved downward from the position shown in the drawing, the link member 64 and the detent rod 63 remain in contact with each other. Accordingly, when the user pushes the operation unit 62, the user is constantly required to apply a force countering the resultant force of the biasing force of the torsion coil spring 67 and a force biasing the detent rod 63 upward. As a result, the responsiveness of the operation unit 62 does not significantly change, and the user does not feel uncomfortable.
In this manner, by biasing an operation unit in the same direction as the direction in which it is pushed, the user feels no discomfort when pushing the operation unit. However, such a gearshift lever needs the link member. This increases the number of components and complicates the structure of the overall gearshift lever. Thus, there is still room for improvement from the viewpoint of practical application.